I have smoked a turkey for the last few years. I got my brine down and my wood ready but due to my wife's family and mine wanting me to do one I am going to have to do 2 at the same time. I have a home built 55 gallon drum smoker with a fire box. For 2 birds do I have to double my time? Am I looking at 12 hours for 2 12lb birds or does it still stay at the 6-7 hour mark?